Reset mechanism for thermal cutout switches



Jan. 19, 1932'. M. E. HENNING RESET MECHANISM FOR THERMAL GUT-OUTSWITCHES Filed June 16. 1930 "nmmli CURRENT SUPPLY Patented Jan. l9, 1932 UNITED- STATES PATENT OFFICE moon: 1:. nmmme, or DES mourns, IOWA,Assmnon'ro 9min mno'rnrc swrron 00., or was memes, IOWA, A conronarron,on Iowa.

RESET MECHANISM FOR THERMAL CUTOUT SWITCHES Application filed June 16',1930; Serial in. 481,546.

The object of my present' invention is to rovide a reset mechanism forswitches which ave overload cutouts of current responsive type, themechanism being simple and efi'ective in its operation.

A further object is to provide a reset mechanism for thermal cutoutswitches or the like which will positively prevent the possibility ofmanually holding the switch in closed circuit position when the currentresponsive cutout device is in open circuit position.

More particularly, it is my object to pro vide the combination with aswitch member movable to open and closed circuit positions and a currentresponsive circuit opening mechanism for the switch member. of a resetmember movable to reset the current responsive mechanism and at the sametime operable to move the switch member to open circuit position wherebyto prevent closure of the switch member except when the reset member isreleased orthe current responsive means when reset is in position toallow movement of the switch member to closed cir cuit position;

With these and other objects in view my invention consists in theconstruction, arrangement and combination of the various parts of mydevice, whereby the objects contemplated are attained, as hereinaftermore fully set forth, ointed out in my claims and illustrated in t eaccompanying drawings. Although the invention is susceptible of avariety of embodiments, it is unnecessary to fully describe andillustrate more than one in order to give a full understanding of theinvention both from its structural and functional standpoints.Accordingly ment of the invention in the accompanying drawings in which:

Figure 1 is a perspective view of an automatic switch structure showingit diagrammatically connected with a mechanical re frigerator. 1

Figure 2 is an enlarged front elevation of the switch showing the coverremoved.

Figure 3 is an enlarged sectional view on the line 33 of Figure 2.

I have illustrated a preferred and desirable embodi- HEISSUED Figure 4is a sectional view on the line of Figure 3 and v Figure 5 isadiagrammatic view of the parts and electrical connections of theswitch. On the accompanying drawings. I have used the reference numeralto indicate a switch casing. A cover 12 is rovided therefor. Theparticular switch i lustrated is of the automatic type forcontrolling-the supply of electriccurrent to a machine such as the motor14 of a mechanical refrigerating sys-,

.tem 16, the temperature of which controls the switch through atemperature responsive element 18 and connecting tube 20. I

The tube 20 is connected with a fitting 22 which communicates with 'abellows 24 wherebyvariations in temperature in the element 18 willcontract and expand the bellows 24. A head 26 of the bellows 24 carriesa pin 28, which engages one side of a primary lever 30. The lever 30 ispivoted on a pin 32.

A spring 34 is provided with a contacting with the opposite side of tmary lever 30 whereby the the bellows 24 and balances tween the 'bellowsand the spring. The spring 34 "is preferably adjustable.

A switch arm 38 is pivoted on a pin 40and operativel connected with theprimary lever 30 by a llllk 42. A permanent magnet 44 in the expansionor contraction of the belin 36 e prispring opposes the lever 30 belows24 will move the switch arm to open and closed ,positions, depending onthe temperature or pressure action u on the bellows.

A stationary contact p ate 46 is connected with a contact prong 48 andcarriesa contact 50: The switch arm 38 carries a con-' tact 52. Theswitch arm 38 and consequently the contact 52 are connected by aflexible lead54 with oneendof a heating element 56. The other end of theheating element 56 is connected'by a wire 58 with a second contact prong60. v

In connection with the movable switch arm 38, a thermal cutout mechanismis provided consistingof a cutout arm 62 and a thermal ill) latch 64therefor. The cutout arm 62 is pivoted on a pin 66 and is provided withan exten sion 68 1n position to engage the switch arm 38, when a spring70 is allowed to move the cutout arm 62 toward the right, as viewed inFigure 2. The thermal latch 64 is a strip of bimetallic metal having oneend anchored to a fitting 72, which is pivoted on a screw 7 4. Thethermal bar 64 is provided with an opening 7 6 into which a latch lug 78of the thermal cutout arm 62 may extend when the arm 62 is in latchedposition. The fitting 72 is connected with a second thermal bar 80mounted in opposition to the thermal latch 64 so as to prevent externaltemperature changes from affecting the operation of the cutout.

From the foregoing description, it will be obvious that .when the cutoutlever 62 is latched by the thermal latch 64, the extension 68 cannotcontact with the switch arm v38 and normal automatic operation of theswitch arm is had. Whenever an overload current flows through theswitch, however, it will raise the temperature of the heating element 56for warping the thermal latch 64 to an unlatched position whereby thespring 70 will cause the released arm 62 to swing to the right, asviewed in Figure 2 and the extension 68 will engage the switch arm 38and separate the contacts 50 and 52. Thus any damage to the motor 14 isprevented when an overload, caused by clogging of the refrigerationpipes or any other cause, is thrown onto the motor.

My reset mechanism consists of a reset lever 82 pivoted on the pin 66and having on one end an ear 84 adapted to engage the cutout lever 62and on its other end an extension 86 adapted to engage the switch lever38. A reset button 88 is engageable with the car 84 for moving thelevers 82 and 62 to reset position. A release button 90 is provided forunlatching the bar 64 from the latch lug 7 8 of the cutout lever 62whereby the switch may be allowed to open the circuit by a manualcontrol.

In my co-pending application, Serial No. 448,256, filed April 29, 1930,the button 88 contacted directly with the cutout arm 62 and there wasdanger in the use of such a switch that someone, when desiring the motorto continue-to operate for even a short period of time after the thermalcutout had opened the switch, would hold the button in and thus hold thecircuit in closed position and possibly burn out the motor or causeother damage because of the excessive current flowing through thecircuit. The main object of my present invention is to eliminatev suchdanger and I have, therefore, provided the reset lever 82 withthe lug 86to engage the switch arm 38 and positively hold it in an open circuitposition while the button 88 is being held in. Thus the switch can moveagain to closed circuit position onl after the reset bottom 88 has beenrelease and providing the latch 64 is not again moved to unlatchedposition by excessive current flowing through the heating element 56.Thus it becomes necessary to locate and correct the trouble before thecircuit can be re-estab lished and maintained.

All danger of improper holding of the switch. in closed circuit positionis eliminated.

Instead of the button 88, the reset lever 82 maybe moved to resetposition by any other desired means.

Some changes may be made in the construction and arrangement of thevarious parts of my device without departing from the real spirit andpurpose of my invention, and it is my intention to cover by my claims,any modified forms of structure or use oi mechanical equivalents, whichmay be reasonably included within their scope.

I claim as my invention:

1. In a reset mechanism for thermal cutout switches, the combinationwith a switch member normally movable to open and closed circuitpositions, circuit opening means for independently moving said switchmember to open circuit position and a thermal latch for. said means, ofa reset member movable to latch said circuit opening means by means o'l;said thermal latch, said reset member being operatively connected withsaid switch member to move it to open circuit position upon suchlatching movement of the reset member.

2. In a reset mechanism of the character disclosed, the combination witha switch having a stationary contact and a movable contact and currentresponsive mechanism for disengaging said movable contact from saidstationary contact, of reset means for said mechanism comprising a resetmember movable to resetting position and operative ly connected with theswitch for opening the same when the reset member is so moved.

3. In a reset mechanism of the character disclosed, the combination witha switch having a stationary contact and a movable contact and currentresponsive mechanism for disengaging said movable contact from saidstationary contact, of reset means for said mechanism comprising apivoted reset lever movable to resetting position and engageable withthe switch for opening the same when the reset lever is so moved.

4. In a reset mechanism of the character disclosed, the combination witha switch member normally movable to open and closed circuit positionsand current responsive -mechanism to independently move the switchmember to open circuit position upon an overload current flowing thruthe circuit controlled by the switch member, of reset means for saidmechanism comprising a movable reset member and means for moving thesame to resetting position and simultaneously therewith, moving saidswitch member to open circuit position. 5. In a reset mechanism ofthecharacter disclosed, the combination with power means, a switch membermovable thereby to open and closed circuit positions and currentresponsive mechanism to move the switch member to open circuit positionindependntlyof said power means upon an overload current flowing thruthe circuit controlled by the switch member, of reset means forsaidmechanism comprising a reset member movable to reset position andsimultaneously engageable with the switch member to move the same toopen circuit position.

6. In a reset mechanism of the character disclosed, the combination withpower'means, a switch member movable thereby to open and closed circuitpositions and current responsive mechanism to move the switch to opencircuit position independent of said power means uponan overload currentflowing thru the circuit controlled by the switch r member, of resetmeans for said mechanism comprising a reset leverpivotally mounted andmeans to impart pivotal movement to said reset lever to move the same-toreset position, said reset lever having an operative connection-withsaid switch member to move the same to open circuit position when thereset leveris' moved to. reset position.

7. In a reset mechanism of the character as disclosed, the combinationwith a switch member normally movable to open and closed circuitpositions and current responsive mechanism to move the switch memberindependent of its normal movement to open 40 circuit position upon anoverload current flowing thru the circuit controlled by the switchmember, of reset means; for said mechanism comprising'a reset leverpivotally mounted and means to impartpivotal 4s movement to said resetlever to move the same to reset position, said reset lever beingengageable with said switch member to move the same to open circuitposition when the reset lever is moved to reset position. a

5:} Des Moines, Iowa, June 6, 1930.

I MALCOLM E. HENNING.

